Detection of pollutants

The use of nanomaterials is important in environmental science and technology in terms of their applications in green chemistry, pollution prevention, remediation of contaminated soils and water, and sensing and detection of pollutants. These applications are directed towards environmental improvement and pollution control. 

We all agree that the continuous on-line/in situ detection of pollutants in water and wastewater should be the best practice for true quality monitoring. This is particularly relevant for the monitoring of emerging pollutants if we consider that for the other types of pollutants, there already exist some suitable systems. The main topic of this chapter is to show that there are some available devices for the on-line monitoring of emerging pollutants or, at least, some interesting developments. But first, it is indispensable to outline several important points in order to be sure that all potential users or developers of on-line/in situ measurement systems do know the main limits and constraints of the exercise. 

Dr. Rohlfing s research interests include the experimental characterization of transient molecules relevant to combustion processes, linear and nonlinear laser spectroscopies, trace detection of pollutants, molecular beam and mass spectrometric studies of carbon and metal clusters, and vibrational relaxation dynamics. He is the author of approximately 50 peer-reviewed articles, holds membership in the American Chemical Society and the American Physical Society, and is a fellow of the American Association for the Advancement of Science. 

The application of optical immunosensors for environmental monitoring started some years ago. The use of sensors for the measurement of pollutants is a viable alternative in environmental control where it is important to develop sensors of small size, that are reliable, sensitive and selective, for operation in situ and produced by a low cost technology. Several applications have been reported mainly applied to pesticide detection (herbicides, biocides, etc.). The SPR technology has been applied to many environmental problems, mainly for the detection of pollutants in the aquatic environment, such as... 

Molander, S. and H. Blanck. 1992. Detection of pollution-induced community tolerance (PICT) in marine periphyton communities established under diuron exposure. Acjuat. Toxicol. 22 129-144. 

This bioluminescent system has been widely used as reporter system for the detection of pollutants because of its high sensitivity. The co-substrate (FMNH2) and substrate (R-CHO) required for this reaction do not accumulate in the cell, but their levels depend on the level and balance of metabolism. Thus the bioluminescent reaction is directly linked to the cells metabolic activity, and so in models using lux as the reporter system, the light emission capacity is directly affected by factors such as changes in cell growth and dissolved oxygen concentration (Nelson and Lawrence, 1980). 

Even quantitative determinations can be performed using biological-physiological methods. These are discussed by Jork and Weins [114] using the example of enzymatic in situ detection of pollutants. 

In addition to the fiber sensors, there have been numerous reports on remote fiberless optical detection of pollution from stationary sources. Mobile remote sensors can have cost advantages over on-site instruments and also are much more versatile. Pollutants in smokestack emissions have been identified by irradiation with a laser from a mobile unit equipped with a telescope, a monochromator, and low-noise detection electronics. The gases and particles in the plume scatter the laser light in various directions. A fraction is scattered back to the receiver and analysed to detect the amount and type of gas in the plume. Many of these methods await their application to fiber-optic sensing schemes which are inherently safer than direct laser spectroscopic schemes. 

Giardi MT, Koblizek M, Masojidek J. Photosystem Il-based biosensors for the detection of pollutants. Biosens Bioelectron 2001 16(9-12) 1027-33. 

Avramescu A, Rouillon R, Carpentier R. Potential for use of a cyanobacterium Synechocystis sp. immobilized in poIy(vin)dalcohol) Application to the detection of pollutants. Biottchnol Tech 1999 13 559-562. 

Compared with classical analytical methods such as gas chromatt raphy, HPLC, atomic absorption or mass spectrometry, the detection of pollutants by biosensors is generally less specific. These devices provide valuable information on a class of pollutants rather than a mere information about a specific compound, although the use of mutants that are resistant to specific pollutants can render them more selective. Biosensors provide valuable information about the real biological effects of the pollutants in a sample since phytotoxicity is determined from the measurement of electron transport activity, photocurrent or photosynthetic oxj en evolution. It is important to note that althoi the PSII complex is sensitive to various pollutants (herbicides, heavy metals, sulphites, nitrates, carbonates), its susceptibility to these compounds is highly variable, tanging from nanomolar to milhmolar concentrations. 

Enzymes-based biosensors are well reported in the literature for chemical toxicity screening. The sensor devices produced using enzymes are usually simple and easy to fabricate, inexpensive, and sensitive to low levels of toxicants. Immobilization of enzymes on the electrode surface can include adsorption, covalent attachment, or film deposition using a range of procedures [68-70]. The sensor system relies primarily on two enzyme mechanisms catalytic transformation of a pollutant and detection of pollutants that inhibit or mediate the enzyme s activity. In catalytic enzyme biosensor, the enzyme specific for the substrate of interest (toxin in this case)... 

Current Yongjiang River Basin Environmental Risk Research focused on three aspects the detection of pollutants, water pollution accident emergency and quality management. 

In recent years, the microarrays based on killifish complementary DNA (cDNA) and algae Synechocystis cDNA have been constructed in order to evaluate environmental stresses at the levels of genes [53-55]. The application and development of such microarrays (against a variety of environmental pollutants) may result in rapid and easy detection of pollutants. However, such microarray technology requires a lab-based specific device. In order to use it as the DNA biosensor, downsizing of the whole system is required. Success of such downsizing may make it possible to do on-site assessment. 

Bedioui, F., S.G. Granados, and C. Bied-Charreton (1999). Metalloporphyrin, met-allophthalocyanine and related macrocycle complex-based film modified electrodes Review of selected significant designs and applications to the electrochemical detection of pollutants. Recent Res. Dev. Electrochem. 2(1), 91-108. 

In its earlier stages of development dating from around the 1960s, the emphasis in environmental chemistry was upon detection of pollution, cataloging its adverse effects, and controlling pollutants once they were produced. This resulted in an... 

Several decades of industrialization have changed the enviromnent drastically, leading to all sorts of pollution. Water pollution, being one of most important issues related to daily life, has always been addressed and mtmitored by various means of analytical tools. Different electrochemical sensors for the detection of pollutants in water have been well established, which can be categorized into the following (i) poten-tiometric sensors, (ii) amperometric sensors, (iii) voltammetric sensors, and (iv) conductometric sensors. In this chapter, we will introduce the fundamentals, applications, advantages, limitations, and recent trends for the development of each type of sensors. 

In general, pollutants exist in the enviromnent at very low concentrations and, therefore, the detection of these pollutants becomes poor. The selective detection of pollutants in environmental samples is important, since many... 

OPTOCHEMICAL MICROSENSORS AND SENSOR SYSTEMS FOR DETECTION OF POLLUTANTS IN GASES AND AQUEOUS SOLUTIONS... 

G Braunlich, G Gamer, MS Petty. Detection of pollutants in water by Raman spectroscopy. Water... 

Figure 5 Calibration curves for the dinitrophenol herbicide DNOC in aqueous solution when using different techniques (A) PDS Photothermal deflection spectroscopy, (B) TL thermal leasing, (C) PIS Photothermal Interferometric spectroscopy, (D) PAS a photoacoustic spectroscopy, (E) a conventional spectrophotometer Cary 2400. Reproduced with permission of SPIE from Faubel W (1997) Detection of pollutants in liquids and gases. In Mandelis A and Hess P (eds) Life and Earth Sciences. Progress in Photothermal and Photoacoustic Science and Technology, Vol III, Chapter 8. Bellingham SPIE.

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